The first of the stamps printed bilingually throughout the sheet,
the initial printings being produced in London by Waterlows. The
printing plates were then shipped to South Africa and subsequent
printings were made in Pretoria. In general the London printings are in
colours that appear deeper and have a “richer” appearance. Side
marginal examples are easily identified, as the London printings are
imperforate at the left margin and perforated through the right margin.
It is vice-versa for Pretoria printings. Right lower marginal pairs or
blocks also have markings that identify which plate the stamps are
printed from. The ½d, 1d & 4d Triangle stamps were issued on 1st
January 1926, this being a Sunday. As most post offices were closed on
this date then covers dated 2nd January 1926 are usually
accepted as first day covers.

It must be noted that although the 4d triangle stamp is treated as a
separate entity to the ½d, 1d & 6d by most catalogues, it was also
issued on the same day and is a definitive stamp. It is not the easiest
stamp to find used on cover and such covers are sought after. The
narrow margin stamps were delivered to post offices in packets of 60,
already cut to shape. The stamps were later supplied to post offices in
uncut sheets, hence the wide margin stamps were available and are
popular in multiples.